Oe käteng hu sa'nokä sa'nok tokro hospital fėtrr. Poe 'efu ke sėltsanspxin.
I was spending time with my grandma at the hospital today. She is not feeling well

Note: I didn't see grandma on the learn Na'vi app English>Na'vi so I said mom's mom

Yeah we don't know anything much about family at all except: mother father parents daughter son child brother sister sibling. But with those we can describe many relatives that we have in the way that you did. Nicely done